Boilers on Opentherm

[JohnMo]

Trying to learn something new.

 

I know - Opentherm is a communication protocol between controlling thermostat and boiler and is a two way thing. So thermostat is say set at 21 and the control mechanism is to drip feed energy into house to keep house temp pretty constant.

 

Also heard it mentioned that not all Opentherm control algorithms are equal, some manufacturers run boiler harder than others.

 

Does Opentherm work in reality?

 

Do you get lots of boiler cycles?

 

Do you have cost savings in gas?

 

Does it work for radiators and UFH?

 

Assume UFH would need to be directly connected and no mixer valve at UFH manifold to get best gains?

[MikeGrahamT21]

OpenTherm is just one of many Digital Connectivity methods, this is from the Tado installer manual:

 

 

All of the digital methods allow two way comms, and the setting of things like flow temperature on the fly from the controller, Tado for example now has flow temperature optimisation which changes on an hourly basis depending on outdoor temperature. It also has the ability to request a specific amount of heat, as opposed to analog which is a simple on or off, and the boiler would modulate down based upon the temperature of the water, this in theory stops huge overshoots of temperature from happening, and therefore wasted energy.

 

An UFH system loop would always require a mixer, due to the low temperature requirements, I suspect this could be omitted if it was the only heat source, with no wall hung rads.

 

Does it save on Gas, it should do in theory, but I have no data to back that claim up, as I've always ran this particular boiler in Opentherm mode, so have no comparison. And boiler cycles, i've never really taken note of how many times it fires per hour so couldn't say for sure

[JohnMo]

1 hour ago, MikeGrahamT21 said:

An UFH system loop would always require a mixer, due to the low temperature requirements, I suspect this could be omitted if it was the only heat source, with no wall hung rads

That is how mine is connected - no mixer or pump, also I have no radiators to demand a higher flow temp.

 

Running fixed flow temp, although boiler thinks it's running WC, via a resistor, and a 0.1 hysterisis on/off thermostat switching between a normal and setback.